Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
On Nov. 29, 1954, a yearling Landrace boar was admitted to the Stange Memorial Clinic. The accompanying history was as follows: The boar had settled several sows in spite of difficulty in serving them and normal libido seemed to be somewhat retarded. A noticeable quantity of ejaculate appeared to be evacuated from the vulva of the sows serviced. Occasionally, the penis was observed protruding from the prepuce 4 to 6 inches. In all other aspects the animal appeared normal.
Mulder, John B.
"Intermittent Preputial Diverticulum Phimosis in a Boar,"
Iowa State University Veterinarian: Vol. 17
, Article 11.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol17/iss2/11